MicroBooNE: LarSoft
Simulation & PMT Response
Tests
Jessica Esquivel
August 6 2009
Nevis Labs, Columbia
University
1
Outline/Acknowledgments





2
MicroBooNE Overview
SuperNova Neutrinos
Hardware
Software
Future Work/Conclusion




Mike Shaevitz
Lesli Camilleri
Willian Seligman
Gary Cheng
MicroBooNE Overview

Liquid Argon Time
Projection Chamber
–
–

3
Booster neutrino beam
Neutrinos from the Main
Injector(NuMi)
Primary Physics done is
studying the low energy
excess seen in MiniBooNE
Published: “Unexplained Excess of Electron-Like
Events from a 1 GeV  Beam”, PRL 102, 101802 (2009)
MicroBooNE Overview
 gg
e+e4
MicroBooNE Overview

Ionization electrons drift
to 3 recording planes
–
–
2 Induction planes U, V:
+- 60 to vertical
1 collection plane Y:
vertical.
Induction planes
U
V
Collection
plane
Y
Electro
ns
5
MicroBooNE Overview

Scintillation light is
collected by PMT's
–

6
Used to determine the
time when event occured
PMT's are coated with
a Tetraphenylbutadiene (TPB) to shift
the scintillated light to
visible light.
8” PMT
Super Nova Neutrinos

Neutrino Signal is the first to emerge from a
Supernova.
–

All Large LArTPC's should have the capability of
collecting supernova neutrino data.
–
–
–
7
Can give information about the early stages of core
collapse
MicroBooNE is the beginning of large scale LArTPC's
Cold Electronics will reduce electric noise
LAr purity for longer drifts
MicroBooNE Overview
8
Hardware: PMT point response

First tests tested the
point dependency on
the PMT.
22.5°
45°
67.5°
90°
9
0°
Hardware: PMT point response


10
Poor Correlation
Unsteady Pulse
Generator
Hardware: PMT response as a
function of angle
11
Hardware: Calculated vs
Experimented

12
Fresnel's Equations shown below were used
as a checkpoint calculations to make sure the
data that was being collected was close to the
calculated data.
Hardware: Angle of Incidence Vs
Relative Mean

13
Plot shows the calculated
mean using Fresnel's
Equations plus the data
collected at three different
points on the PMT
Hardware: Angle of Incidence Vs.
Relative Mean

Discrepancies calculated and measured data
include:
–
Human error in measuring the angle of incidence.




–
14
2.65% on average over all the points
6.6% at point A
1.45% at point D
1.3% at point G
Index of refraction of PMT was unknown, 1.5 was
used for calculating purposes instead.
Hardware: Photodetector
response in electrostatic field

In the MicroBooNE experiment, the PMT’s
will be exposed to an electric field of
500V/50cm
–
15
We are recreating this by building a blackbox with
two aluminum plates mounted 50cm away.
Hardware: PMT E-Field Results


Turning on the +500V has no
effect on the PMT pulse height +500V
(Mesh)
500V was then increased to
700V
–

Ground
(Cryostat)
LED
It acts as a Faraday cage
PMT was also reversed
–
16
Oscilloscope
The cathode is grounded
Therefore all outside field lines
terminate on it.
–

Still no effect
Pulser
Still no effect: There is an
electrostatic shield
50 cm
16
Software

The LArSoft software package has been run for NUE-e
interactions with incoming energies of:
–
–
–

17
50MeV
100MeV
150MeV
The reason why LarSoft was run for such low energies was to be
able to simulate supernova neutrinos which happen on a low
energy scale.
Software: Event Display


18
All events were
shown in this form.
To extract
information, a
program was
needed.
Software

Histograms have been created for:
–
–
–
–
–
–
19
Incoming Neutrino/Anti-Neutrino Energy
Outgoing Lepton Energy
Outgoing Neutrino/Anti-Neutrino Energy
Theta between the Incoming Neutrino Vector and Outgoing
Lepton Vector
Number of Voxels relative to the incoming Energy
Number of Voxels vs the Energy of Electrons
Software
20
Software
21
Software
22
Software




23
Neutrinos are left-handed and
electrons are as well.
Before colision, the angular
momentum is zero.
Direction isn't important after
collision because in any
direction, angular momentum
will be conserved.
This results in a flat neutrino
energy distribution
Software



Anti-Neutrinos are righthanded
Before Colision angular
momentum is +1.
Direction is important
because angular momentum
needs to be conserved.
–

24
Anti-neutrinos must emerge in
the forward direction in the
center of mass
This results in a peaked
energy distribution.
Software: Theta between Neutrino
and lepton
Mean Theta in
Degrees is:
13.32 degrees
25
Software: Voxel

A Voxel is a 3D pixel that divides the energy
deposited in the Liquid Argon into X, Y and Z
cubes
–
26
These voxels are then what drifts to the simulated
wire chambers.
Software
Energy: 50MeV Mean: 57.04
Energy: 100MeV Mean: 115.6
Energy: 150MeV Mean: 172.6
27
Software

28
Plot shows the
correlation between the
Number of Voxels and
the Energy of an
Outgoing Electron
Future Work




Understanding why some events are thrown out.
Plot the electrons coming from an NUEbar-e interaction
separately from a NUE-e interaction.
Plot Energy of Voxels vs Energy of Electron
Do PMT response tests on the PMT being used in
MicroBooNE
–
29
Using a more sophisticated setup to reduce human error